Supervisory signal for telephone-switchboards.



A 0 9 1 4 1 E N U J D E T N E T A P H I R R A U Q 0 M L Tu SUPERVISORYSIGNAL FOR TELEPHONE SWITGHBOARDS.

APPLICATION FILED HAY 9. 1902.

H0 MODEL.

lnverwtor: James I MfiQuarrie,

wllr'wesses:

Attor nay EiltfZM- m: norms virus on. mom-01110.. WASHINGTON/D: c

UNITED STATES Patented June 14, 1904.

PATENT OEEICE.

ELECTRIC COMPANY, ILLINOIS.

OF CHICAGO, ILLINOIS,'A CORPORATION OF SUPERVISORY SIGNAL FORTELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 762,432, dated June 14,1904.

Application filed May 9, 1902. Serial No. 106,567. 1N0 model.)

To all 10/1/0711, it may concern.-

Be it known that I, JAMES L. MoQUAEnIE, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illi- 5 nois,have invented a certain new and useful Improvement in SupervisorySignals forTelephone-Switchboards, of which the following is a full,clear, concise, and exact description. My invention relates to asupervisory signal I for telephone-switchboards, and has for its objectto provide an improved signal which will be especially adapted for usein connection with telephone-exchange systems where a central battery isemployed to supply current to the transmitting-telephones of connectedlines. In such systems the magnets which control the supervisory signalsare placed in conductors of the cord-circuit in the path of current tothe lines, so that these magnets are excited during the connection aslong as the substation-telephones are in use, and the signal controlledby the magnetmust therefore be arranged to'be displayed when the magnetbecomes inert; but this is the 5 condition of the magnet when thecord-cir cuits are not in use and it is desired that the signal shouldnot be displayed at such times, but should be displayed to indicate acall for disconnection while the cord-circuit is in use. 3 In accordancewith my invention the supervisory signal is controlled through theagency of two magnetavindings, one of which is included in the path ofcurrent to the line and controlled by the substation-switch, and theother is included in a local circuit closed in making connection Withthe terminal switch or spring-jack of any line. The last-mentionedmagnet-winding controls mechanism which normally prevents the display ofthe signal,

4 so that the signal can never be displayed unless connection is madewith some line. During the existence of such connection the display ofthe signal is dependent upon the flow of current in the othermagnet-winding. The

excitement of said magnet-winding causes the concealment of the signalwhich is displayed when the flow of current ceases.

I will describe my invention more particularly by reference to theaccompanying drawings, which illustrate the preferred embodi- 5 mentthereof.

Figure l is a diagram illustrating two telephone-lines extending fromsubstations to a central office, with a pair of plugs and theirplug-circuit at the central oifice for uniting the lines, saidplug-circuit being equipped with automatic supervisory signals inaccordance with my invention. Fig. 2 is a detail view of the supervisorysignal device, showing an alternative position.

The same parts are designated by the same reference characters in bothfigures.

The telcphone-lines illustrated are of a type which is well known in theart, the equipment of the lines being such as is common for the 5 commonbattery relay switchboard. The usual telephone-switch a is provided atthe substation to control the flow of battery-current in the line. Theusual spring-jack or terminal switch is provided, havingtwo line-springs7 connected, respectively, with the line conductors and also having athird contact or thimble 7),which is connected to earth through thecut-oiI relay 0, as is usual in such systems. The plug-circuit forconnecting lines together has the usual link conductors 1 2, which unitethe tip and ring contacts 4 (Z of each plug (Z with the correspondingcontacts of its mate. Each plug has also the usual third contact orsleeve (Z which is adapted to register with the thimble 7) of anyspring-jack into which a plug may be inserted. The grounded centralbattery 0 is shown connected in a bridge of the cord-circuit between thewindings of a repeating-coil in the usual manner. A super- 5 visorysignal device is associated with each plug and consists of anelectromagnet whose armature controls a responsive devicesuch, forexample, as a movable indicator or target-and a second electromagne'tassociated 9 with the first and serving to operate mechanism whichnormally prevents the actuation or display of the signal, but which iswithdrawn by said second magnet when excited to leave the signal orresponsive device under the complete control of the first-mentionedmagnet.

The first magnet is connected in one of the conductors of theplug-circuit in the path of current from the battery to the line withwhich the plug may be connected, and the second magnet is connected inalocal circuit 3, which is completed in registering contacts of the plugand spring-jack. I have shown the two magnets 7" mounted in alinement,the outer ends of the magnet-cores being united by a U-shaped yoke-pieceit, which extends underneath the magnets and serves to support theirarmaturesf 0, respectively. The armatures are mounted back to backbetween the opposed ends of the magnet-cores, and the armature g ofmagnet is arranged to overbalance the armaturef" and hold the latter inthe position it would assume it attracted, said armature f beingbalanced to recede from its attracted position when relieved of theweight of armature r A light arm 7" is carried by the armatu re f, saidarm extending forward underneath the yoke-piece and having at its end anindicator or target Z1. hen the armature f" is in its unattractedposition, the target 7" is displayed in the opening of ashield 71: toconstitute a visible signal, as shown in Fig. 2; but when said armaturef is in its attracted position the target Z" is lifted above theopeningin the shield, and so is concealed. The armature 7 serves as alocking device to prevent the display of the signal irrespective of thecondition of magnetf; but when the magnet r is excited this lockingmeans is overcome and the target will be concealed or displayedaccording to the excited or inert condition of the magnetf. \Vhen theplugcircuit is idle,- the targets of the supervisory signals will beconcealed, as shown in Fig. 1. \Vhen, however, a plug is inserted in thes 'iring-jack of a line, the conductor 3, which extends from the freepole of battery 0 to the third contact {5" of the plug,will be completedto earth by way of the thilnble of the jack, into which the plug may beinserted, so that the magnet will remain excited while the plug is inuse. The target b will then be controlled by the magnet f. As long asthe telephone at the substation of the connected line is in use thecircuit of the battery 0 will be completed through said magnet and thetarget Z2 will be concealed; but when the subseribcr replaces histelephone the flow of current through the magnet f ceases, so that itallows its armature f to fallback, displaying the target 7;" to indicatea signal for disconnection.

I claim- 1. The combination with a telephone-line and. atelephone-switch at the station thereof for changing the circuit of theline in the use of the telephone, a spring-jack for the line in aswitchboard, and a plug and plug-circuit for making connectiontherewith, of a supervisory signal comprising an indicator, an armatureconnected with the indicator, and a magnet acting on said armatureadapted to conceal the indicator when excited, a mechanical deviceindependent of said armature also adapted to conceal theindicator, and asecond elcctromagnct controlling said device, a local circuit closed inmaking connection with the line including said last-mentioned magnet,said first-mentioned magnet controlling the indicator being included inthe telephone-line to be responsive to current therein, substantially asdescribed.

2. The combination with a telephone-line and a telephone-switch at thestation thereof for changing the circuit of the line in the use of thetelephone, a spring-jack for the line in a switchboard, and a plug andplug-circuit for making connection therewith, of a supervisory signalcomprising an indicator, an armature connected with the indicator, and amagnet acting on said armature adapted to conceal the indicator whenexcited, a mechanical device independent of said armature also adaptedto conceal the indicator, and a second electromagnet controlling saiddevice, a local circuit closed in registering contacts of thespring-jack and plug including said last-mentioned magnet, saidfirst-mentioned magnet controlling the indicator being included in thetelephone-line to be responsive to current therein, substantially asdescribed,

In witness whereof I hereunto subscribe my name this 15th day of March,A. D. 1902.

JAMES L. MOQUARRIE.

\Vitnesses:

EDWIN H. SMYTIIE, FREDERICK A. \VATKINs.

